Japanese Patent Laid-Open Publication No. JP-A-07-184361 discloses a vehicular generator-motor apparatus having both the function as a three-phase motor for starting an engine mounted in a vehicle and the function as a three-phase alternating current generator for charging a battery.
The above-mentioned vehicular generator-motor apparatus includes a motor-generator and an integrated rectifier. The motor-generator includes a magnetic rotor, a stator core, and a three-phase armature winding. The stator core is fixed to a housing of the motor-generator. The three-phase armature winding is winded around the stator core. The magnetic rotor rotates inside the perimeter of the three-phase armature winding winded around the stator core.
The integrated rectifier is fixed to an inner surface of a rear housing of the motor-generator. The integrated rectifier includes six MOS power transistors arranged on a silicon (Si) substrate.
The integrated rectifier controls an electric current supplied to the three-phase armature winding by performing switching control of the six MOS power transistors, thereby directing the motor-generator to serve as an electric motor. The integrated rectifier also converts an alternating voltage generated by the motor-generator using engine torque into a direct-current voltage, thereby directing the motor-generator to serve as an electric power generator.
The vehicular generator-motor apparatus is a motor-generator having the integrated rectifier for controlling driving of the motor generator provided on the end surface thereof.
The above-mentioned vehicular generator-motor apparatus, however, is not configured with consideration given to cooling of the MOS power transistors constituting the integrated rectifier. This leads to problems. For example, improving the heat resistance of the MOS power transistors leads to an increase in size of the integrated rectifier, resulting in deterioration of the mountability of the vehicular generator-motor apparatus.
Also, providing the integrated rectifier separately from the motor-generator leads to an increase in the number of wiring harnesses, resulting in deterioration of the mountability of the vehicular generator-motor apparatus.